Increased walking and cycling, and fewer cars, would have a much greater impact on health than use of low-emission vehicles, in both rich countries like the UK and middle-income countries such as India. This is the conclusion of the second paper in the Lancet Series on Health and Climate Change, written by James Woodcock, London School of Hygiene and Tropical Medicine, UK, and colleagues.
The authors estimate the health effects of alternative urban land transport scenarios for two settings—London, UK, and Delhi, India. For each setting, they compared a business-as-usual 2030 projection (without policies for reduction of greenhouse gases) with scenarios that had motor vehicles with lower carbon emissions, increases in active travel/less motor traffic, and a combination of both (towards sustainable transport). They developed separate models that linked transport scenarios with physical activity, air pollution, and risk of road traffic injury.
The team found that, in both cities, reductions in carbon dioxide emissions through an increase in active travel and less use of motor vehicles had considerably greater health benefits than the increased use of lower-emission motor vehicles. In London the benefit was over 40 times greater, and in Delhi over 7 times greater. Combining active travel and lower-emission motor vehicles would give the largest benefits.
For London, the largest gains were from reductions in ischaemic heart disease (10—19% of total ischaemic heart disease burden; equivalent to 1950—4240 premature deaths in one year prevented when applied to the London population), cerebrovascular disease (10—18% of cerebrovascular disease burden; 1190—2580 deaths), dementia (7—8% of dementia disease burden; 200-240 deaths), and breast cancer (12—13% of total breast cancer disease burden; 200—210 deaths). There would also be reductions in the burden of both depression and colon cancer.
In Dehli, the largest health gains were from an 11—25 % decrease in total ischaemic heart disease burden (equivalent to 2490—7140 premature deaths in one year prevented when applied to the Delhi population, an 11—25% decrease of the total cerebrovascular disease burden (1270—3650 deaths), and diabetes (6—17% of total diabetes disease burden; 150—460 deaths).There would also be reductions in the burden from acute respiratory infections in children, lung cancer, and depression.
Although reducing motor vehicle use would decrease the injury risk for existing pedestrians and cyclists, if many more people walked and cycled there might be an increase in the number of pedestrian and cycle injuries, since more people would be exposed to the risk that remained. The team found that in Delhi the trade-off between these two effects led to an overall reduction in road traffic injuries (27%—69%, equivalent to 1170—2990 fewer premature deaths in Delhi per year) whilst for London it led to an increase in road traffic injuries (19—39%, equivalent to 50—80 extra premature deaths in London per year). Although there is still considerable uncertainty around the injury findings the results strongly indicate that any possible increase in injuries would be outweighed by benefits from increased physical activity and less air pollution.
The authors say: "Creation of safe urban environments for mass active travel will mean prioritisation of the needs of pedestrians and cyclists compared with those of motorists. Walking or cycling should be the most direct, convenient, and pleasant options for most urban trips. Policy makers should divert investment from roads for motorists towards provision of infrastructure for pedestrians and cyclists. Compared with cars and trucks, pedestrians and cyclists should have direct routes with priority at junctions. Strict controls for HGVs in urban areas are key safety prerequisites for cyclists."
They conclude: "Important health gains and reductions in CO2 emissions can be achieved through replacement of urban trips in private motor vehicles with active travel...Technological measures to reduce vehicle pollutants might reduce emissions, but the health effect would be smaller...An increase in the safety, convenience, and comfort of walking and cycling, and a reduction in the attractiveness of private motor vehicle use (speed, convenience, and cost) are essential to achieve the modal shifts envisaged here."
All contacts below are from London School of Hygiene and Tropical Medicine, UK.
James Woodcock T) ) +44 (0)20 7927 2127 E) james.woodcock@lshtm.ac.uk
Professor Ian Roberts T) +44 (0)207 958 8128 E) ian.roberts@lshtm.ac.uk
Dr Phil Edwards T) +44 (0)20 7958 8112 E) phil.edwards@lshtm.ac.uk
London School of Hygiene and Tropical Medicine Press Office. T) +44 (0) 20 7927 2073 E) Sally.Hall@lshtm.ac.uk / Gemma.Howe@lshtm.ac.uk
For full Series paper 2, see: http://press.thelancet.com/tlhacc2.pdf
Journal
The Lancet